What's he saying?
"Poor soul, the centre of my sinful earth / [ ] these rebel powers that thee array;"
My poor soul, the center of my sinful body, ??? these rebellious powers that surround you;
"Why dost thou pine within and suffer dearth / Painting thy outward walls so costly gay?"
Why do you waste away within my body and suffer from lack of nourishment, yet decorate your outward appearance with such costly and cheerful adornment?
"Why so large cost, having so short a lease / Dost thou upon thy fading mansion spend?"
Why do you spend so much on something so short-lived as your fading body?
"Shall worms, inheritors of this excess / Eat up thy charge? is this thy body's end?"
Will the worms, who will take ownership of your decorated body after you die, eat up your bounty? Is this the purpose of beautifying your body?
"Then soul, live thou upon thy servant's loss / And let that pine to aggravate thy store;"
If that is so, then, my soul, let my body's loss be your gain, and let my body suffer for your enrichment;
"Buy terms divine in selling hours of dross; / Within be fed, without be rich no more:"
Sell your hours of earthly waste in exchange for time in heaven; spend resources on yourself, within the body, and no longer concern yourself with outward beauty.
"So shalt thou feed on Death, that feeds on men / And Death once dead, there's no more dying then."
Thereby will you consume Death, which merely feeds on the bodies of men - and once Death is dead, you (the soul) cannot die.
What's he saying?
Sonnet 146 is best known for its deeply introspective, quasi-religious, philosophizing style hardly found elsewhere in the sequence. Here the narrator addresses not the dark lady but rather his own endangered soul, grappling to understand why it has squandered so much of its precious time and resources on transient earthly indulgences. He relies heavily on the imagery of financial bondage to characterize the pointless materialism he is trying to overcome in his search for salvation from the sinfulness of greed.
The poet begins the sonnet with a metaphor: "Poor soul, the centre of my sinful earth." Here "earth" stands for the body, the instrument and bearer of sin, within which the soul is kept captive. The poet asks his soul why it allows itself to suffer for the sake of its "sinful earth" in lines 3-4: "Why dost thou pine within and suffer dearth / Painting thy outward walls so costly gay?" In the second quatrain we find another metaphor for the body in the "fading mansion" of line 6 - the mortal home of the poet's suffering soul. Again the poet questions his soul's expenditure on bodily "excess," knowing that it will all go to the worms in the end anyway.
The imagery of financial bondage dominates this sonnet; almost every line of the sonnet contains at least one word that is somehow related to money. The purposes of the imagery appear to be, first, to characterize the bondage of body and soul to the claims of beautification, and second, to highlight the sinfulness of earthly greed. Both earth and body are bound to sin, while soul is bound to body; only by enriching the soul itself can the soul be freed of its bonds and achieve immortality. It is as though the soul has a debt to pay off before it may escape Death's eternal doom, and as such the narrator compels his soul to "Buy terms divine in selling hours of dross" in order to set itself free.
Sonnet 146 is therefore also an example of the narrator's constant battle against the inevitable fate of death. This sonnet, however, posits a light of victory for the narrator, for in it he claims to have intuited the secret of eternal life. In lines 9-10 we read, "Then soul, live thou upon thy servant's loss / And let that pine to aggravate thy store." In other words, rather than concern itself with material waste, his soul is instead advised to devote itself to its own self-cultivation; for the soul can outlive the body, and even conquer Death, as we see in line 13: "So shalt thou feed on Death, that feeds on men / And Death once dead, there's no more dying then."
Note that line 2 in the original Quarto begins with the words "My sinful earth." This is taken to be a printer's error, since it repeats the end of the preceding line and is syntactically inappropriate. Needless to say, many scholars have attempted to fill the gap with educated guesses.